Population bases
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Population bases. Part II: introductory discussion on a new population concept. Giampaolo Lanzieri (EUROSTAT). A few facts. The internationally recommended concept of 'usually resident population' is not (fully) adopted by all countries

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Population bases

Population bases

Part II:

introductory discussion on

a new population concept

GiampaoloLanzieri (EUROSTAT)


A few facts

A few facts

  • The internationally recommended concept of 'usually resident population' is not (fully) adopted by all countries

  • There are some difficulties in the implementation of this concept

  • The usage of the same data source for population estimates in censuses and in annual statistics is spreading

Meeting of the Experts Group on Population and Housing Census


Some problematic issues in the usual residence concept

Some problematic issues in the usual residence concept

  • Conceptual:

    • Shifting time frame of reference

    • 'Continuous' time is somehow a slippery definition

    • Based on subjective element (intention of stay)

  • Empirical:

    • No effective control of the permanence in the place of usual residence

    • Difficult measurement of the intention of stay

    • It may not fit national data sources and national practices/laws

Meeting of the Experts Group on Population and Housing Census


Starting from scratch

Starting from scratch

  • What is a 'population'?

    • Definition in space and time + qualifying characteristic(s)

  • What is the most intuitive characteristic?

    • To be 'present'

  • Should all people just 'present' to be included?

    • No, only those who stay 'for a while'

Meeting of the Experts Group on Population and Housing Census


Present population is changing in continuous time

Present population is changing in continuous time

1 year

Meeting of the Experts Group on Population and Housing Census


Foundations of population concept

Foundations of population concept

  • The definition of the population requires two dimensions: presence and duration of stay

  • The inclusion of individuals is depending on defined threshold(s): eligibility(E)

  • These two dimensions need to be somehow combined

Meeting of the Experts Group on Population and Housing Census


An ideal measure person years

An ideal measure: person-years

  • A correct measure, combining the two dimensions of population

  • It refers to a period of time (preferably in years)

  • The total population (P)expressed in person-years is then given by the number N of those present times their length of stay Le (longer than threshold):

    P = N x Le

  • It can be estimated from measures taken at moments in time

Meeting of the Experts Group on Population and Housing Census


Period and moment in time

Period and moment in time

  • The persons-years refer to a period, possibly a year (e.g., the population in the year 2013)

  • At any moment in time during that year, the population 'density' is given by Pt= N¦ L>Le, i.e. by those person who at that moment are present and with length of stay longer than Le

  • In a given period (e.g., a year):

Meeting of the Experts Group on Population and Housing Census


Some difficulties

Some difficulties

  • The implementation would require a very developed statistical system. In particular, it could be based on network of municipal registers

  • The concept may be not straightforward at first glance

  • Users may not like decimals when referring to population rounding as possible solution: if person-years more than 0.5, then the person is included in the population, otherwise not

Meeting of the Experts Group on Population and Housing Census


A pragmatic solution

A pragmatic solution

  • We keep the reference to:

    • A defined period

    • The 'rounded' version of person-years

    • The eligibility

  • …that we translate in:

    • The calendar solar year

    • The criteria of most-of-the-year/time

    • A period of uninterrupted presence

Meeting of the Experts Group on Population and Housing Census


Implementation of the new concept

Implementation of the new concept

  • The eligibility is the declared presence at a defined address for a period of at least/more than 3 months/90 days

  • A person is included in the population for a given year if (s)he has been present for most of the year

  • If necessary, the preferred reference moment in time is the end of the year

Meeting of the Experts Group on Population and Housing Census


Annual resident population

Annual resident population

  • The annual resident population is composed of those resident persons who have been present on the territory for most of the year of reference

  • A resident person spends on the territory a period of at least/more than 3 months/90 days of declared presence without interruption(s), of which at least one day in the year of reference

Meeting of the Experts Group on Population and Housing Census


Annual resident population cont

Annual resident population (cont.)

  • 'Annual' refers to the fixed time frame (calendar year), 'resident' to the continuous staying

  • The population figure refers to the year as a whole

  • It can be referred also to a moment in time (person-years can be estimated if required)

Meeting of the Experts Group on Population and Housing Census


Annual non resident population

Annual non-resident population

  • The annual non-resident population is composed of those persons who have been present on the territory for most of the year of reference, but with no period of at least 3 months/90 days of declared presence without interruptions

Meeting of the Experts Group on Population and Housing Census


Examples of annual non resident persons

Examples of annual non-resident persons

  • Persons who do not declare their presence on purpose (e.g., illegal migrants, persons with no interest to links to the territory)

  • Homeless and similar categories without fixed residence (but present on the territory)

  • Persons who stay more than 6 months in the territory but in fragmented periods (e.g., persons staying regularly one week per month, or on weekends)

Meeting of the Experts Group on Population and Housing Census


Population of a territory in a year

Population of a territory in a year

Meeting of the Experts Group on Population and Housing Census


Choice of population of reference

Choice of population of reference

  • The size of the annual resident population is verifiable (declared presence) and theoretically precise

  • The size of the annual non-resident population is most likely derived by estimations

  • The choice between the annual resident population and the annual population (thus including non-resident) may depend on the specific needs

Meeting of the Experts Group on Population and Housing Census


A few remarks

A few remarks

  • The annual (resident) population is potentially a new concept of population for statistical purposes

  • Oriented towards use of population registers and new ways of census/annual statistics production

  • Need of (many) further refinements of the concept

    This is just an introduction to a discussion on a single population definition

Meeting of the Experts Group on Population and Housing Census


Questions

Questions

  • Could it be added to the list of population definitions?

  • What are the problems you see in implementing this concept of population?

  • …?

    For any further contact on this matter:

    [email protected]

Meeting of the Experts Group on Population and Housing Census


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